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Message-ID: <c2307cb4c3f1af46da138f3410738754691fbb3d.1753274085.git.leonro@nvidia.com>
Date: Wed, 23 Jul 2025 16:00:03 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: Leon Romanovsky <leonro@...dia.com>,
Christoph Hellwig <hch@....de>,
Jason Gunthorpe <jgg@...dia.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Christian König <christian.koenig@....com>,
dri-devel@...ts.freedesktop.org,
iommu@...ts.linux.dev,
Jens Axboe <axboe@...nel.dk>,
Jérôme Glisse <jglisse@...hat.com>,
Joerg Roedel <joro@...tes.org>,
kvm@...r.kernel.org,
linaro-mm-sig@...ts.linaro.org,
linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-media@...r.kernel.org,
linux-mm@...ck.org,
linux-pci@...r.kernel.org,
Logan Gunthorpe <logang@...tatee.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Robin Murphy <robin.murphy@....com>,
Sumit Semwal <sumit.semwal@...aro.org>,
Vivek Kasireddy <vivek.kasireddy@...el.com>,
Will Deacon <will@...nel.org>
Subject: [PATCH 02/10] PCI/P2PDMA: Introduce p2pdma_provider structure for cleaner abstraction
From: Leon Romanovsky <leonro@...dia.com>
Extract the core P2PDMA provider information (device owner and bus
offset) from the dev_pagemap into a dedicated p2pdma_provider structure.
This creates a cleaner separation between the memory management layer and
the P2PDMA functionality.
The new p2pdma_provider structure contains:
- owner: pointer to the providing device
- bus_offset: computed offset for non-host transactions
This refactoring simplifies the P2PDMA state management by removing
the need to access pgmap internals directly. The pci_p2pdma_map_state
now stores a pointer to the provider instead of the pgmap, making
the API more explicit and easier to understand.
Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
drivers/pci/p2pdma.c | 42 +++++++++++++++++++++-----------------
include/linux/pci-p2pdma.h | 18 ++++++++++++----
2 files changed, 37 insertions(+), 23 deletions(-)
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index fe347ed7fd8f4..5a310026bd24f 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -28,9 +28,8 @@ struct pci_p2pdma {
};
struct pci_p2pdma_pagemap {
- struct pci_dev *provider;
- u64 bus_offset;
struct dev_pagemap pgmap;
+ struct p2pdma_provider mem;
};
static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap)
@@ -204,8 +203,8 @@ static void p2pdma_page_free(struct page *page)
{
struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page_pgmap(page));
/* safe to dereference while a reference is held to the percpu ref */
- struct pci_p2pdma *p2pdma =
- rcu_dereference_protected(pgmap->provider->p2pdma, 1);
+ struct pci_p2pdma *p2pdma = rcu_dereference_protected(
+ to_pci_dev(pgmap->mem.owner)->p2pdma, 1);
struct percpu_ref *ref;
gen_pool_free_owner(p2pdma->pool, (uintptr_t)page_to_virt(page),
@@ -270,14 +269,15 @@ static int pci_p2pdma_setup(struct pci_dev *pdev)
static void pci_p2pdma_unmap_mappings(void *data)
{
- struct pci_dev *pdev = data;
+ struct pci_p2pdma_pagemap *p2p_pgmap = data;
/*
* Removing the alloc attribute from sysfs will call
* unmap_mapping_range() on the inode, teardown any existing userspace
* mappings and prevent new ones from being created.
*/
- sysfs_remove_file_from_group(&pdev->dev.kobj, &p2pmem_alloc_attr.attr,
+ sysfs_remove_file_from_group(&p2p_pgmap->mem.owner->kobj,
+ &p2pmem_alloc_attr.attr,
p2pmem_group.name);
}
@@ -328,10 +328,9 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
pgmap->nr_range = 1;
pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
pgmap->ops = &p2pdma_pgmap_ops;
-
- p2p_pgmap->provider = pdev;
- p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) -
- pci_resource_start(pdev, bar);
+ p2p_pgmap->mem.owner = &pdev->dev;
+ p2p_pgmap->mem.bus_offset =
+ pci_bus_address(pdev, bar) - pci_resource_start(pdev, bar);
addr = devm_memremap_pages(&pdev->dev, pgmap);
if (IS_ERR(addr)) {
@@ -340,7 +339,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
}
error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings,
- pdev);
+ p2p_pgmap);
if (error)
goto pages_free;
@@ -973,16 +972,16 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
}
EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
-static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
- struct device *dev)
+static enum pci_p2pdma_map_type
+pci_p2pdma_map_type(struct p2pdma_provider *provider, struct device *dev)
{
enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
- struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
+ struct pci_dev *pdev = to_pci_dev(provider->owner);
struct pci_dev *client;
struct pci_p2pdma *p2pdma;
int dist;
- if (!provider->p2pdma)
+ if (!pdev->p2pdma)
return PCI_P2PDMA_MAP_NOT_SUPPORTED;
if (!dev_is_pci(dev))
@@ -991,7 +990,7 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
client = to_pci_dev(dev);
rcu_read_lock();
- p2pdma = rcu_dereference(provider->p2pdma);
+ p2pdma = rcu_dereference(pdev->p2pdma);
if (p2pdma)
type = xa_to_value(xa_load(&p2pdma->map_types,
@@ -999,7 +998,7 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
rcu_read_unlock();
if (type == PCI_P2PDMA_MAP_UNKNOWN)
- return calc_map_type_and_dist(provider, client, &dist, true);
+ return calc_map_type_and_dist(pdev, client, &dist, true);
return type;
}
@@ -1007,8 +1006,13 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
struct device *dev, struct page *page)
{
- state->pgmap = page_pgmap(page);
- state->map = pci_p2pdma_map_type(state->pgmap, dev);
+ struct pci_p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(page_pgmap(page));
+
+ if (state->mem == &p2p_pgmap->mem)
+ return;
+
+ state->mem = &p2p_pgmap->mem;
+ state->map = pci_p2pdma_map_type(&p2p_pgmap->mem, dev);
}
/**
diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index b502fc8b49bf9..27a2c399f47da 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h
@@ -16,6 +16,16 @@
struct block_device;
struct scatterlist;
+/**
+ * struct p2pdma_provider
+ *
+ * A p2pdma provider is a range of MMIO address space available to the CPU.
+ */
+struct p2pdma_provider {
+ struct device *owner;
+ u64 bus_offset;
+};
+
#ifdef CONFIG_PCI_P2PDMA
int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
u64 offset);
@@ -144,10 +154,11 @@ enum pci_p2pdma_map_type {
};
struct pci_p2pdma_map_state {
- struct dev_pagemap *pgmap;
+ struct p2pdma_provider *mem;
enum pci_p2pdma_map_type map;
};
+
/* helper for pci_p2pdma_state(), do not use directly */
void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
struct device *dev, struct page *page);
@@ -166,8 +177,7 @@ pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
struct page *page)
{
if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
- if (state->pgmap != page_pgmap(page))
- __pci_p2pdma_update_state(state, dev, page);
+ __pci_p2pdma_update_state(state, dev, page);
return state->map;
}
return PCI_P2PDMA_MAP_NONE;
@@ -185,7 +195,7 @@ static inline dma_addr_t
pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
{
WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
- return paddr + to_p2p_pgmap(state->pgmap)->bus_offsetf;
+ return paddr + state->mem->bus_offset;
}
#endif /* _LINUX_PCI_P2P_H */
--
2.50.1
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